The wiring up is a very simple matter. The battery M has one end connected up with one terminal of a switch N, while the other terminal of the switch has a wire connection with the terminal plugs B, B, in the cylinder heads.
The other end of the battery is connected with the metal of the engine, which may be indicated by the dotted line O which runs to the rock shaft C, and thus forms a complete circuit.
The operation is as follows: When the key P of the switch is moved over so that it contacts with the terminal N, the battery is thrown into the circuit, and the current then passes to the plug B of the first cylinder, as the finger D in that cylinder is in contact with that terminal, and it passes along the finger D, and rock-shaft C, to the metal of the engine, and passes thence to the battery, this course being indicated by the dotted line O.
At the same time, while cylinder No. 2 is also connected up with the battery, the shoulder of the rod H has drawn the finger D from its contact with the plug B, hence the current cannot pass in that direction.
As the cam I, of cylinder No. 1, turns in the direction of the arrow, the rod drops down and suddenly makes a break in the terminal of this cylinder, causing the ignition, to be followed by a like action in No. 2.
The Magneto in the Circuit.—To insure the life of the battery, so that it may be in service only during that period at the starting, when the magneto is not active, the latter is so placed in the circuit, that, at the starting, when, for instance, the automobile is being cranked, it is cut out by the switch on the dash board.
In [Fig. 40], a simple two-pole switch is used. With the magneto it is necessary to have a three-point switch, R, and a plain coil S is placed between the switch and battery.
One side of the magneto T is connected by wire U with one of the points of the switch R, and the other side of the magneto is connected with the metal of the engine, which is indicated by the dotted line V.